public class HumanTest {
    public static void main(String[] args) {
        System.out.println("正常方法调用");
        Human human = new Human();
        human.eat();

        Southerner southerner = new Southerner();
        southerner.eat();

        Northerner northerner = new Northerner();
        northerner.eat();

        System.out.println("多态方法调用");
        Human human1 = new Southerner();
        human1.eat();

        Human human2 = new Northerner();
        human2.eat();

        Southerner southerner1 = (Southerner) human1;
        southerner1.eat();

        Northerner northerner1 = (Northerner) human2;
        northerner1.eat();
    }
}
